The present invention relates to a hydraulic coupling for feeding fluid-driven actuators, particularly for distributing pressurized oil among a plurality of hydraulic motors mounted on a rotating structure. The invention can be used in particular in drum feeders for feeding bars to multispindle automatic lathes.
Conventionally a multispindle automatic lathe is a machine tool comprising a plurality of machining stations which are distributed around a horizontal axis and in which specific machining operations are performed on a bar fed by a feeder. These machinings are, for example, screw cutting, turning, end-facing, parting and so forth.
The bar feeder is substantially constituted by a drum which is rotated about said horizontal axis by said lathe and comprises a plurality of concentric tubular guides which are angularly distributed around the rotation axis; an advancement device is associated with each guide and causes the advancement of the bars, taken from a magazine and inserted in the guides, toward the lathe. At the end of each individual machining, the drum rotates by the same angle that lies between the individual stations, so that the front ends undergo successive machinings.
After the drum has completed a rotation through 360.degree., the machining cycle is complete and the machined part is removed, while a new bar segment is made to advance toward the lathe to undergo the intended machinings.
It is known to use, as a device for the advancement of each bar in the corresponding guide, a chain or another similar element provided with a bar pusher sliding in the guide and actuated by a fluid-driven motor. The pressurized fluid is distributed to the individual motors by using a rotary distributor which is mounted on the rotation axis of the drum and is provided with mechanical devices for controlling the delivery and return of the oil that feeds the motors. Conventional rotary distributors entail the drawback that they do not allow optimum use of the machining stations of the lathe in case of very simple machinings of the parts. For example, if the simple parting of parts from a bar and the forming of a bore at one end are required, most of the machining stations are not used and act only as transit stations.